Do you hear the knocking sound regardless volume and frequency? If you gently push the woofer inwards without playing music, do you hear a scraping noise? Have you tried to turn the speaker upside down and listen for loose parts? Is the woofer dented?
Living room: Sigberg Audio Manta/10D subs, MiniDSP SHD.
Den: Tannoy Precision 8 iDP/TS112 iDP sub, MiniDSP SHD Studio.
In the cupboard: Some bits and pieces of a Phantom Silver 1. gen.
My Phantom Voyage
Den: Tannoy Precision 8 iDP/TS112 iDP sub, MiniDSP SHD Studio.
In the cupboard: Some bits and pieces of a Phantom Silver 1. gen.
My Phantom Voyage
